Aircraft control apparatus



March 2, 1965 c. M. PERKINS AIRCRAFT CONTROL APPARATUS 3 Sheets-Sheet 1Filed June 22, 1955 IN VEN TOR. OORLES M. PERKINS u m ammn I hmfimuwnmmdzoy .2. mm. mm. 1533 19: w! m 2.. E W. .1 3 512,5 5 s E h u k H u Hffi r i l l I I. I L I l l m1 4 4 3 O 1 mom mn.\ 1 m nmb n in 2% Q? ismom) 9% fin a? 2m March 2, 1965 c. M. PERKINS 3,171,279

AIRCRAFT CONTROL APPARATUS Filed June 22, 1955 s Sheets-Sheet 3 usn'rourRELEASE TRANSFER 1.29. ACGELEROMETER INVENTOR. GORLES M. PERKINS THERMALOVERRIDE AUTO-LEVEL CONTROL 420 AUXILIARY lNDlCATOR TRANSFER M 6.ATTORNEY United States Patent 6 3,171,279 AIRCRAFT CONTROL APPARATUSCorles M. Perkins, Anoka, Minm, assignor to Minneapolis- HoneywellRegulator Company, Minneapolis, Minn, a corporation of Delaware FiledJune 22, 1955, Ser. No. 517,211 Claims. (Cl. 73-178) This inventionpertains to aircraft bombing systems and in particular to aircraft loftand toss bombing systems. Previous loft and toss bombing systemscomprise a vertical gyro or equivalent such as a gyro horizon indicator,a timer and an accelerometer. The timer is used together With-aknowledge of the aircrafts speed to establish a pull-up point; thevertical gyro is used to establish a bomb release angle as Well as toprovide pitch and roll data for indicating the flight path 'of theaircraft; the indicator gives a visual indication of the flight path ofthe aircraft to the pilot, and the accelerometer provides informationfor controlling the curvature of the pull-up maneuver. While these priorart bombing systems work fairly well, they suffer from certaininaccuracies in that they rely upon the vertical gyro or gyro horizon toprovide steering information during the pull-up portion of the maneuver.To obtain optimum results in loft and toss bombing operations, it isessential that the aircraft, during the pullup portion of the maneuver,remains in a plane which is perpendicular to the earth and whichincludes the target. The prior art systems using a vertical gyro orequivalent such as a horizon indicator for presenting information to thepilot during the pull-up portion of the maneuver become less and lessuseful until at a point where the planes longitudinal axis isperpendicular to the earth, they are useless as to sensing or presentinginformation relative to displacement of the aircraft about its rollaxis. Since a displacement of the aircraft about its roll axis resultsin a change of aircraft heading, it follows that in bombing systems ofthis type, it'is essential to know at all times the exact roll attitudeof the aircraft. It also is essential for optimum results to know theplanes yaw attitude during the pull-up portion of the maneuver. Thus adeviation in roll attitude of the aircraft will result in the aircraftassuming a new heading after the roll deviation has been correctedunless the yaw deviation produced by the roll deviation has also beendetected and corrected. The present invention is an improvement over theprior art loft bombing systems in that instead of using a vertical orroll-pitch gyro or equivalent for steering information during thepull-up maneuver, a horizontal or roll-yaw gyro sensing deviations ofthe aircraft about its roll and yaw axes is used. Thus, a system of muchhigher accuracy is provided. The present invention comprises a verticalgyro, a horizontal roll-yaw gyro, an accelerometer, and an indicator.During the run-in or approach phase of the operation, the indicatorshows roll and pitch of the aircraft as sensed by the vertical gyro.This is useful for navigational purposes and also indicates to the pilotthat the vertical gyro is operating properly which is a prerequisite toa proper release of the weapon during the pull-up maneuver. During thepull-up maneuver, the indicator shows yaw and roll as sensed by theyaw-roll gyro instead of roll as sensed by the vertical gyro and showsacceleration of the aircraft about its pitch axis as sensed by theaccelerometer instead of pitch as sensed by the vertical gyro. Thus, ifthe plane starts to deviate about its roll axis during the pull-up theresultant deviation about its yaw axis as well as the roll deviationwill be presented to the pilot as a deflection of a single indicator.The pilot then not only has to correct for roll but also for yaw inordervto have the indicator resume its normal position. As long as thepilot controls the craft so as to keep the indicator in its normalposition, he knows that the craft is on the proper heading or returningto the proper heading.

It is therefore an object of this invention to provide an improved loftand toss bombing attitude indicating system. a a r Other and morespecific objects of the invention including the operation of loftbombing systems embodying my invention, will be set forth more fully inand become apparent from a reading of the following specification andappended claims in conjunction with the accompanying drawings in which:

FIGURE 1 andFIGURE 2 together schematically show an improved loftbombing system;

FIGURE 3 is a modification of the system shown in FIGURES 1 and 2 and isadapted to be a substitute for the portion of the basic system shown inFIGURE 2; and

FIGURE 4 is a front view of an indicator of the type that may be used onthe subject system.

' 'I'hepresentloft bombing system comprises a vertical gyro 10preferably of the cageable type such as that-shown in the Brown PatentNo. 2,645,129. Gyro 10 is schematically shown and comprises a rotorhousing 12 supported for rotation in a gimbal 14 which in turn issupported for rotation in suitable frame means 16, the axis of rotationof gimbal 14 in frame 16 being at to the axis of rotation of rotorhousing 12 with the respect to gimbal 14. Erection motors 18 and 20receiving energization from an erection motor transformer 22 are eachcontrolled by a pair of gravity sensitive mercury switches 24 and 26which, as is well understood by-those skilled in the art, respond to theearths gravitational force so as to maintain the spin axis of gyro 10perpendicular to the earths surface. An erection cutout relay 28 isadapted, when energized to interrupt the energization circuits forerection motors 18 and 20. Roll and pitch pick-ofi potentiometers 30 and34 comprising respectively resistive portions 31 and 35 and wipermembers 32 and 36 are used as signal producing means for developing asignal proportional to deviation of the aircraft about its roll orlongitudinal axis and its pitch or lateral axis.

Gyro 10 has a caging mechanism similar to theabove mentioned Brownpatent which is caged by spring means, not shown, and which iselectrically uncaged by electromagnetic means including a holdingsolenoid 38, a stepping solenoid 39 and a stepping switch 40.

In addition to the pick-olf potentiometer 34, a pair of sector switches42 and 45 are associated with the pitch axis of vertical gyro 10. Sectorswitches 42 and 46 respectively comprise contacts 43 and 47 which aredisplaced in accordance to relative rotation between gimbal 14 and frame16 of the gyro. The sector switches also comprise respectivelyadjustable contacts 44 and 43 which are capable of being independentlyadjusted by suitable manual adjusting means 45 and 49. Thus, byadjusting the relative positions of contacts 44 and 48, the point atwhich contact arms 43 and 47 come in contact with contacts 44 and 48 maybe varied from any value between zero and in pitch of the craft uponwhich gyro 10 is mounted. Sector switch 42 may be identified as thenormal release switch and sector switch 46 as the alternate releaseswitch. In the usual mode of operation, these switches are preset sothat switch blade 43 will engage contact 44 at a different pitchattitude than that at which switch blade 47 engages contact 48.

The system also comprises a horizontal gyro 60 (see FIGURE 2) which ismounted on the aircraft so that its spin axis is normally parallel tothe lateral or pitch axis of the aircraft and which, therefore, willsense displacement of the aircraft about its roll or longitudinal axisand yaw axis. Thus a rotor housing 62 is pro vided and is suitablyjournalled in a gimbal 64 which in turn is journalled by suitable meansin frame 66. A pair of pick-off potentiometers 68 and 72 are provided asa means of developing a signal proportional to displacement of theaircraft about its yaw and roll axes and respectively comprise resistiveportions 69 and 73 and wipers 70 and 74. In general horizontal gyro 60may be similar to vertical gyro with the exception that it does not havean erection system. A further difference is that provision of a secondcaging system which provides quick uncaging of rotor case 62 in additionto the spring and e'lectromagnetically uncaged 'caging system of thetype described in connection with vertical gyro 10. Thus, horizontalgyro 60 has a holding solenoid 76, stepping solenoid 77, and a steppingswitch 78 for uncaging rotor case 62, and, to this extent, is similar tothe vertical gyro 10. In addition, horizontal gyro 60 has a cagingsolenoid 80 which operates a caging system completely independent of thefirst mentioned caging system.

The caging solenoid 80 with its associated caging mechanism may begenerally similar in principle to that shown in the Tanner Patent No.1,451,928. Thus solenoid 80 would be mounted on frame 66 and actuates asolenoid plunger, not shown, which engages rotor case 62 when coil 80 isenergized so as to cage or lockv rotor case 62 with respect to frame 66.Spring means, not shown, serve to retract the plunger away from rotorcase 62 when coil 80 is deenergized thus providing a quick release. Aslong as caging solenoid 80 is energized, 'rotor case 62 will be lockedwith respect to frame 66 and the spin axis of the gyro 60 will be heldparallel to the lateral axis of the aircraft. The reason for having anadditional both caging mechanisms simultaneously which results in cagingsolenoid 80 keeping the gyro caged whereas energization of the cagingmechanism including holding solenoid 76 and stepping solenoid 77overpowers the spring caging means, not shown, and results in thatcaging system uncaging the gyro. However, as long as caging solenoid 80remains energized the gyro still remains caged. Associated with thecaging mechanisms is a limit switch 82 having movable arm 83 and a pairof contacts 84 and 85. Normally switch arm 83 is in contact with fixedcontact'84 but when the caging mechanism including the holding solenoid76 and the stepping solenoid 77 have uncaged gyro 60 switch arm 83 isdisplaced so as to engage fixed contact 85.

Gyro 60 also comprises an uncaged relay 86 including a condenser 87 inparallel with the coil thereof, relay 86 having two movable switch arms88 and 92as well as fixed contacts 89, 90, and 93.

A three-position angle selector switch 96 is provided in the system andit comprises a pair of switcharms 97 and 98 which are ganged so as to besimultaneously moved to any one of the three positions shown by asuitable adjustment 99.

The system also comprises a timer or intervalometer 106 which maygenerally be of the type shown in the Haydon Patent 2,506,784. Timer 106generally comprises a direct current electric motor 107, anelectromagnetic clutch 108 including a clutch coil 109, and a cam member110 having a raised portion 110 and driven when clutch 108 is energized,by rotation of motor 107.'

Motor 107 has one terminal grounded as at 50 and is adapted to receiveenergization through a fixed contact 111 which cooperates with a movablecontact blade 112 which is adapted to'be displaced by cam member 110 andwhich as adapted to be connected to a source of voltage under certainconditions as will be described below. When clutch coil 1 09 isdeenergized," spring means 114 displace cam 110 to a point where asshown movable switch blade 112 is in engagement with fixed contact 111.After clutch coil 109 is energized rotation of motor 107 driving throughclutch 108 will displace cam so, after a suitable adjustable timeinterval determined by the setting of a manually adjustable knob 115connected to cam 110, switch blade 112 is displaced by cam surface 110'away from fixed contact 111 and into engagement with a second fixedcontact 113.

This system also comprises an accelerometer of the potentiometer typewhich includes a resistive winding 121 one side of which is grounded asat 50 and a wiper member 122. This accelerometer may well be of the typeshown and described in a copending application of C. R. Bonnell, filedAugust 11,1954, Serial No. 449,035. Accelerometer 120 is mounted on theaircraft in such a position so as to sense accelerations of the aircraftalong its vertical or yaw axis.

Another component of the system is an indicator 125 shown schematicallyon FIGURE 2 and mechanically on FIGURE 4. Indicator 125 may be of anysuitable type to perform the necessary indication and as shown comprisesa pair of meter movements 126 and 128 of the galvanometer type, themeter movements when energized being capable of moving pointers 127 and129 respectively. As can be seen in FIGURE 4, pointer 127 is normallyvertical and is adapted to be displaced either to the right or to theleft as shown while pointer 129 is normally horizontal and is adapted tobe displaced up or down as shown. Pointer 127 registers with. a scale127 and will indicate either'roll or yaw of the aircraft, While pointer129 registers with a scale 129' and will indicate either pitch oracceleration of the aircraft about its pitch axis.

The system comprises a plurality of relays. Among these are a releaserelay 130 comprising a winding 131, movable switch blades 132 having anin contact 133; movable blade 134 having an out contact 135; movablecontact 136 having an in contact 137; and movable contact blade 138havingan in contact 139. A timer hold relay 140 has a coil 141; amovable contact blade 142 having an in contact 143; a movablecontactblade 144 having an out contact 145; a movable contact blade 146having an in contact 147; and a movable contact blade 148 having an outcontact 149. A timing complete relay 150 has a coil 151; a movablecontact blade 152 having an in contact 153 and an out contact 1 54 andamovable contact blade 155 which has an in contact 156 and an outcontact 157. A timing start relay 160 has a coil 161; a movable contactblade 1 62having an in contact 163; a movable contact blade 164 havingan out contact 165; and a movable contact blade 166 having an in contact167. A power relay 170 has a coil 171 and a movable contact blade172having an in contact 173. A light out relay (see FIG- URE 2) has acoil 181 and a movable contact blade 182 with an out contact 183. has acoil 191 with a condenser 192 in parallel therewith; a movable contactblade 193 with an in contact 194 and an out contact 195; and a movablecontact blade 196 having an in contact 197 and an out contact 198. Anindicator transfer relay 200 has a coil 201; a movable contact blade 202having an in contact 203; a movable contact blade 204 having an incontact 205 and an out contact 206; a movable contact blade 207 havingan in contact 208; a movable contact blade 209 having an in contact 210and an out contact 211;'a movable contact blade 212 having an outcontact 213; and a movable contact blade 214 having an out contact 215.Coils 131, 141, 151, 161, 171, 181, 191, and 201, are connected at oneside thereof to ground 50.

A bridge network 220 is shown on FIGURE 1 and comprises in part a rollcentering potentiometer 222 having a resistance portion 223 and a wiper224 and a pitch centering potentiometer 226 having a resistance memher227 and a wiper 228. Bridge 220 also includes a. pair of resistors 230and 232 connected in series with.

A release transfer relay the resistive portion 227 of pitch centeringpotentiometer 225 between a junction point 229 and ground 50, thearrangement being with resistive member 227 being between resistances230 and 232. The bridge also includes a pair of resistors 234 and 236 inseries with resistive member 223 of roll centering potentiometer 222being connected between junction point 229 and ground 50, thearrangement being with resistive portion 223 being intermediate ofresistances 234 and 36.

Referring to FIGURE 2 it will be noted that horizontal gyro 60 has abridge network 240 associated with it. This includes a yaw ratiopotentiometer 242 having a resistance portion 243 and a wiper 244; aroll ratio potentiometer 246 having a resistance member 247 and a wiper248; a sensitivity adjustment potentiometer 250 having a resistancemember 251 and a wiper 252. The resistive portion 243 of yaw ratiopotentiometer 242 is connected between the wiper 70 of the yaw pick-offpotentiometer 68 of the horizontal gyro 60 and one side of the resistiveportion 247 of the roll ratio potentiometer 246, the other side of whichis connected to the wiper 74 of the roll pickoif of the horizontal gyro60. The common connection between resistive portions 243 and 247 isidentified by numeral 245. The resistive portion 251 of the sensitivitypotentiometer 250 is connected at one side to wiper 248 of the rollratio potentiometer 246 and at the other side to the wiper 244 of theyaw ratio potentiometer 242. Wiper 244 of the yaw ratio potentiometer242 is connected to in contact 210 of indicator transfer relay 200 andwiper 252 of the sensitivity potentiometer 250 is connected to the incontact 208 of the indicator transfer relay 200. The common point 245between resistances 243 and 247 is connected to the mid-point of avoltage divider consisting of a pair of resistors 254 and 256 which areconnected between ground and a conductor 258 which will be later shownto receive energization from a suitable voltage source during one partof the system operation. It will be noted that one side of each of theresistive portions 69 and '73 of the yaw pick-off potentiometer 6S andthe roll pick-off potentiometer 72 of the horizontal gyro 69 areconnected to said conductor 258 through resistors 260 and 262respectively. The other sides of the yaw and roll pick-oft resistiveportions 69 and 73 are connected to ground through roll centeringpotentiometer 264 and yaw centering potentiometer 266 respectively.

Referring again to bridge 220 shown on FIGURE 1 it will be noted thatpoint 229 between resistors 230 and 234 receives energization when powerrelay 170 is energized. This is done by the manual closing of a mainpower switch 270 which applies power from a source of suitable voltage271 to the winding 171 thereof. Energization of the power relay 1'70completes a circuit between movable switch blade 172 and its in contact1'73 thus applying voltage not only to junction point 229 but also tothe roll and pitch pick-011s 30 and 34 of the vertical gyro 10. It willbe noted that the wipers 32 and 36 of the roll and pitch pick-offsrespectively are connected by wires 32 and 35 to the out contacts 213and 215 respectively of the indicator transfer relay 200. Further; thewiper 224 of the roll centering potentiometer and the wiper 228 of thepitch centering potentiometer 226 are connected by means of leads 224and 228' to the out contacts 211 and 206 respectively of the indicatortransfer relay 200. Thus, when the indicator transfer relay isdeenergized meter movement 126 of the indicator 125 is connected'betweenwiper 32 of the roll pick-off potentiometer 30 and wiper 244 of the rollcentering potentiometer 222. Similarly the meter movement 128 of theindicator 125 is connected between the wiper 36 of the pitch pick-offpotentiometer 34 of the vertical gyro 10 and the wiper 228 of the pitchcentering potentiometer 226. The wipers 228 and 224 are adjusted so thatwhen the aircraft is in straight and 6 level flight the horizontalneedle 129 and the vertical needle 127 of the indicator 125 are at theirzero reference point as shown on FIGURES 2 and 3. Thereafter;

roll pick-off 30 and pitch pick-off 34 to the indicator.

thus giving the pilot a visual indication of any deviation away fromstraight and level flight.

A bridge 230 is provided for modifying the signal from theaccelerometer120. This includes a G calibration potentiometer 282 havinga resistance portion 283 connected between ground 50 and lead 258 and aWiper 284. A G sensitivity potentiometer 285 has a resistance portion286 connected between wiper 284 of the G calibration pot 282 and wiper122 ofthe accelerometer 120. A wiper 287 of the G sensitivitypotentiometer 285 is connected to in contact 203 of the indicatortransfer relay 200 while wiper 284 of the G calibration potentiometer232 is connected to in con tact 205 of the indicator transfer relay 200.It will be appreciated that when lead 258 is energized the poten*tiometer in the accelerometer and the yaw and roll pick-offs 63 and 72of the horizontal gyro 60 are also energized as well as coil 201 of theindicator transfer relay 200. Thus indication of the indicator is.

changed from the roll and pitch pick-offs of the vertical gyro 10 to theaccelerometer 120 and the horizontal gyro in the following manner. Theaccelerometer signal is applied to the horizontal needle 129 through thein contacts 205 and 203 of the indicator transfer relay 200 and thecombined roll-yaw signal of the horizontal gyro 60 is applied to thevertical needle 127 of the indicator 125 through in contacts 208 and 210of the indicator transfer relay 200. Thus the horizontal needle 129 willnow indicate accelerations of the aircraft about its pitch axis whilethe vertical needle 127 will show yaw and/or roll of the aircraft.

A manual yaw-roll. switch 290 is provided as shown in FIGURE 2 andcomprises a pair of contacts 291 and 292 which are adapted to be shortedout by a movable switch member 293.

Operation As indicated above, when main power switch 270 is closed powerrelay 170 is energized thus applying voltage from the source of voltage271 through movable switch blade 172 and its in contact 173 of powerrelay 170 to the bridge 220 as well as to the roll and pitch pickoifs 30and 34 of the vertical gyro 10. Voltage is also applied from the loadside of the switch 270 through a lead 300 to the line side of a startswitch 302. When start switch 302 is closed voltage is applied through alead 304 to the uncaging mechanism for the vertical gyro 10 causing itto uncage and voltage is applied through a lead 306 to the horizontalgyro 60 caging mechanisms. This energizes holding solenoid 76, steppingsolenoid '77 and caging solenoid 80. The energization of holdingsolenoid 76 and stepping solenoid 77 causes that caging mechanism touncage gyro 60. However, since caging solenoid 80 is energized it servesto maintain the caged condition of gyro 60 thus keeping the spin axis ofthe gyro parallel to the lateral axis of the craft. When steppingsolenoid 77 has completely uncaged its mechanism, limit switch 82 isacuated so as to displace movable switch blade 83 into engagement withfixed contact 85. This applies voltage from conductor 306 up to incontact 89 of the uncage relay 86. Closing the start switch 302 alsoapplies voltage through a lead to the motor 107 in the timer 106 bypassing through the cam actuated blade 112 and fixed contact 111.Voltage is also applied to movable switch blade 1660f timing start relayfrom lead 308 through lead 313. Motor 107 rotates but at this pointclutch coil 109 is not energized so that rotation of motor 107 has noeifect on cam 110. Voltage is also applied from conductor 308 to movableswitch blade 162 of the timing start relay 160 through conductor 309; tomovable switch blade 155 of the timing complete relay 150 throughconductor 310; to movable switch blade 152 of timing complete relay 150through conductor 311; and to movable switch blade 144 of timer holdrelay 140 through conductor 312. Timer hold relay 140 is deenergized atthis time so the voltage on movable switch blade 144 is transmittedthrough out contact 145 to out contact 165 of timing start relay 168through a conductor 314. Since timing start relay 160 is deenergized atthis time, the voltage on out contact 165 is transmitted through movableswitch blade 164 and a conductor 315 to fixed contact 135 of releaserelay 130 and from conductor 315 to movable switch blade 146 of timerhold relay 140 through a conductor 316. Release relay 130 is denergizedat this time so the voltage on out contact 135 thereof is transmitted toa light 317 through a conductor 318. Light 317 thus gives the pilot avisual indication that that portion of the system activated by the startswitch 302 is energized. The timing complete relay 150 is deenergized atthis time so voltage is transmitted through movable switch blade 152 tothe out contact 154 thereof through conductor 320 conductor 321 andthence to in contact 139 of the release relay 130 as well as to the coil181 of the light out relay 180 (see FIGURE 2). When this happens a light322 connected to conductor 321 is lit. The voltage applied to lead 306by the closing of start switch 302 is brought to the out contact 183 ofthe light out relay 180 by a lead 3%)7 but goes no further at this timesince light out relay 180 is energized. Voltage also is supplied to outcontact 194 of the release transfer relay 190 by lead 307 but goes nofurther at this time since release transfer relay 190 is deenergized.

Thus, at this time the vertical gyro is uncaged, the roll and pitchpick-offs and 34 are energized and indicator 125 shows any deviations ofthe craft about its roll and pitch axes. When the pilot gets to adesired identification point a bomb switch 326 is closed applying powerfrom the source of voltage 271 through lead 327 and 328 to the timingstart relay winding 161 thus energizing timing start relay 160; tomovable switch blade 142 of the timer hold relay 140 through lead 329;to the movable switch blade 132 of the release relay 130; to switchblades 97 and 98 of the angle selector switch 96 through a lead 331; andthrough a lead 332 to in contact 197 of the release transfer relay 190as well as fixed contact 291 of the manual yaw-roll switch 290.Energization of timing start relay 160 deenergizes the indicator light317 and allows the voltage present on movable switch blade 166 thereofto be applied to in contact 167 and thence through lead 333 to theclutch coil 109 of the clutch 108 thus energizing it which permits themotor 107s rotation to be transmitted to cam 110 which then begins torotate clockwise as shown in the drawing.v

and thence through lead 334 to in contact 147 of timer hold relay 140.When the angle selector switch 96 is in position 1 as shown power flowsfrom movable switch blade 98 through a lead 335 to switch blade 43 ofthe sector switch 42. When the angle selector switch 96 is in either ofpositions 2 or 3 then the power is applied to switch arm 47 of thesector switch 46 through a lead 336., Since switch arms 43 and 47 aredirectly actuated by pitching of the aircraft, it follows that accordingto the setting of knobs and 49 and of the angle selector switch 9-5power will be transferred from switch arms 43 and 47 to the contacts 44and 48 thereof.

, After a predeterminedtime, which may be varied according to the wishesof the pilot by adjusting with knob the initial position of cam 110 withrespect to switch blade 112, cam surface 110 causes switch 112 to moveto the left as shown in FIGURE 1 disengaging it with fixed contact 111and engaging it with fixed contact 113. This temporarily deenergizesmotor 107 and completes a circuit so that the voltage available on lead308 is conducted through switch arm 112 to fixed contact 113 and thencethrough a lead 337 to movable switch blade 148 of the timer hold relay140. Current then flows through the out contact 1490f the timer holdrelay and to coil 151 of the timing complete relay through a lead 338which also energizes the in contact 153 of the timing complete relay150. This causes the timing complete relay 150 to pull in applying thevoltage available on switch arm 152 to in contact 153 thus setting up aholding circuit for the timing complete relay 150 and allows the voltageavailable on switch arm to be applied to in contact 156 which then bymeans of a conductor 339 energizes the timer hold relay winding 141 thuscausing the timer hold relay 140 to pull in. Energization of the timerhold relay 140 allows the voltage available on movable switch arm 142 tobe applied to in contact 143 which then by means of a conductor 340applies voltage to movable contact blades 136 and 138 of the releaserelay 130. Also the voltage available on in contact 147 is transmittedthrough movable switch blade 146, conductors 316 and 315, out contact135 and movable switch blade 134 of release relay 130, and conductor 318to relight indicator lamp 317. Pulling in of the timing complete relay150 removes the voltage from out contact 154 so as to deenergizeconductors 320 and 321, and indicator light 322. Deenergization ofconductor 321 causes the light out relay to drop out. This allows themovable contact blade 182 thereof to engage its out contact 183 which asindicated is energized through leads 306 and 307. This applies a voltagethrough contacts 183 and 182 of the light out relay 180, a lead 350 toout contact 198 of the relay and then through movable contact blade 196thereof through a lead 351 thus energizing conductor 258, describedabove in connection with the bridge circuits 240 and 280 associated withthe horizontal gyro pick-offs and accelerometer pick-off respectively.Energization of conductor 258 not only energizes the yaw and rollpick-offs 69 and 72 of the horizontal gyro as well as the resistivewinding 121 of accelerometer 120 but also energizes indicator transferrelay 200 through a conductor 352 connected between the ungrounded sideof the relay winding 201 and conductor 258. Energization of conductor258 also energizes the uncage relay in horizontal gyro 60 through aconductor 353, out contact 90 of the uncage relay, movable switch blade88 of the uncage relay and a conductor 354 between movable switch blade88 and the uncage relay winding 86. As soon as the uncage relay pulls init breaks its energization circuit between movable contact blade 88 andout contact 90 but condenser 87 holds enough of a charge so as to delaythe drop out thereof long enough so that movable switch blade 88 maypick up new energization from in contact 89 which as indicated above isenergized through conductor 306, movable switch blade 83 and fixedcontact 85 of the limit switch 82. Thus the uncage relay 86 remainsenergized and the circuit is broken between movable switch blade 92 andout contact 93 thereof so as to deenergize the caging solenoid 80 of thehorizontal gyro 60 which now permits the horizontal gyro to becompletely uncaged.

Energization of the indicator transfer relay 200 causes movable switchblades 202, 204, 207, and 209 to come in contact respectively with incontacts 203, 205, 208 and 210. This couples the combined output of theroll and yaw pickoffs 72 and 68 to the vertical needle 127 of theindicator 125 and couples the output of the accelerometer 120 and Gcalibration potentiometer 280 to the horizontal needle 129 of theindicator 125. Thus any change in yaw or roll of the aircraft beingsensed by horizontal gyros 60 will be indicated on the vertical needle127 while all accelerations along the aircrafts vertical or yaw axis aresensed by accelerometer 120 and are compared with the setting of the Gcalibration potentiometer 28% so as to give a visual indication on thehorizontal needle 129 of the indicator 125.

Energization of conductor 258 also energizes the erection cutout relay28 in the vertical gyrolfi so as to deenergize the erection motors 18and 20 associated therewith. This allows the vertical gyro 1% to remainrelatively uninfluenced by accelerations acting upon the mercurycontained in the gravitby sensitive switches 24 and 26.

Referring to the angle selector switch 96 it will be observed that whensaid switch is in position number 3 a connection is established betweenlead 331 and conductor 258. The effect of this is to completely bypassout of the system the operation of timer 106 in that closing of the bombswitch 326 will immediately energize conductor 258 which in turn causesthe horizontal gyro 60 to completely uncage, the accelerometer and theyaw-roll pick-ofis 122, 68 and 72 to be energized as well as energizingthe indicator transfer relay 200. In short, by moving angle selectorswitch to position 3, the timed portion of the operation is eliminated.

When the timing cycle is completed light 322 is extinguished and light317 is relit thus giving the pilot a visual indication that this portionof the maneuver has been completed. The pilot then begins to change thecrafts pitch attitude, pulling up or diving as the case may be. Theindicator 125 provides the pilot with the information needed forcontrolling the craft during this portion of the maneuver. Since it isdesired to maintain a straight heading, the pilot desires to know anychange in roll or yaw of the craft. Thus this information from thehorizontal gyro 69 is presented by the'vertical needle 127 of theindicator 125 and the pilot controls the craft so that needle 127 stayson the zero reference mark. Also, during this portion of the maneuver,it is desired that the pilot maintain a constant acceleration of thecraft along its vertical axis. This is done by setting the wiper 284 onthe G calibration potentiometer 232 to a point corresponding to thedesired number of Gs that the specific maneuver calls for. The effect ofdisplacing the wiper 284- is to unbalance the bridge formed byresistances 283 and 121 between conductor 258 and ground which applies asignal to the meter movement 128 controlling the horizontal needle 129of indicator 125. Thus needle 129 will be displaced away from the zeroposition and can be brought back to the zero position only by the pilotexecuting the maneuver so as to impose an acceleration along thevertical axis of the aircraft that will have an effect on accelerometer129 so as to displace its wiper 122 in an amount suihcient so as tonullify the effect of displacement of wiper 284.

As the planes pitch attitude changes during this portion of themaneuver, relative movement occurs between contacts 43 and 47 of thesector switches 42 and 46 and their respective fixed contacts 44 and 48of the vertical gyro 10. Assuming that angle selector switch 96 is inposition 1, as shown, then, when a pitch attitude has been reached wherecontact between the movable switch blade 43 and its fixed contact 44occurs then voltage is applied from lead 335 through lead 369 to winding131 and in contact 133 of the release relay 130. This causes theenergization of release relay 139 which applies the voltage available onmovable switch blade 136 to in contact 137 and thence through a lead 3&2to out contact 195 of the release transfer relay 190 and thence throughits movable contact blade 193 through a conductor 363 to winding 191thereof. The voltage on lead 362 is also applied (see FIGURE 2) to thecircuit (not shown) controlling the release of a bomb orthe like. Thispulse of energy causes release transfer relay 190 to pull in which 16immediately breaks its energization circuit which would tend todeenergize it. However, condenser 192 in parallel with winding 191causes release transfer relay 190 to hold in until it picks upenergization from in contact 194 through movable blade 193 and lead 363.Movable blade 196 moves over and continues to receive energization, nowthrough in contact 197 so conductor 258 with its accompanying circuitsabove identified continues to be energized. Also when the release relay130 pulls in the light out relay 180 is reenergized through movableswitch blade 138 and in contact 139 and lead 321. I

When angle selector switch 96 is in position 2, the operation of thesystem is substantially the same as when switch 96 is in position 1"except that alternate sector switch 46 has the control over theenergization of release relay 139 instead of normal sector switch 42.

When angle selector switch 96 is in position 3, the operation of thesystem is altered to the extent that as soon as the bomb switch 326 isclosed, conductor 238 is energized (assuming the start switch 302 andpower switch 276 had previously been closed). This uncages thehorizontal gyro 60, energizes the indicator transfer relay 260 so as totransfer indication of meter 125 from roll and pitch to yaw-roll andacceleration about the pitch axis. Knob on timer 1% then can be adjustedso as to immediately energize lead 337 and thus, through timing completeand timer hold relays 159 and 140, energize movable switch blade 136 ofrelease relay 134). Then when the crafts pitch attitude is such thatcontacts 47 and 43 of sector switch 46 close, release relay 130 will beeffective to release the bomb by the energization of lead 362. 1

After release relay 130 pulls in light 322 is relit and light 317 isextinguished thus indicating that release has taken place and serves asa signal to the pilot that he may terminate this portion of themaneuver. The pilot may then release bomb switch 326 which deenergizesconductor 258 so as to deenergize the indicator transfer relay 2% so asto transfer indication on the indicator from roll-yaw and accelerationback to roll and pitch. It will be observed that when conductor 258 isdeenergized by the release of the bomb switch 326 that the uncage relay86 does not become deenergized inasmuch as it is receiving itsenergization from conductor 306 through limit switch 82 and in contact89 of the uncaged relay. Thus the horizontal gyro 60 is still uncagedand should the pilot desire to receive information concerning the rolland yaw as well as acceleration of the aircraft about its pitch axis hemay do so by repressing the bomb button which will reenergize conductor258 and thence indicator transfer relay 2% as well as the bridges 28%and 240 associated with the accelerometer and horizontal gyro fitlspick-otf respectiyely.

The manual yaw-roll switch 290 allows the pilot a manual meansofuncaging the horizontal gyro 60 and transferring indication of theindicator 125 from roll and pitch to yaw-roll and acceleration along thevertical axis. When the bomb switch 326, is closed (subsequent to theclosing of the main power switch 270 and the start switch 302),conductor 332 is energized which applies a voltage to contact 291 ofswitch 2%. Then,shorting of contacts 291 and 292 by movable switchmember 293 applies the voltage to above described conductor 258 touncage gyro 60, etc.

FIGURE 3 As indicated above the circuitry shown in FIGURE 3 represents amodification of the circuitry shown in FIG- URES 1 and 2 together and isintended to be used in place of FIGURE 2. Similar components areidentified by the same identification figures in FIGURE 3 as were usedin FIGURE 2. The modification of the system provides a solution for aproblem that might occur in the operation of the basic system. Theproblem is that the horizontal gyro 60 may be uncaged when the wings 11of the aircraft are not level. Since the spin axis of the horizontalgyro is held parallel to the pitch or lateral axis of the aircraft priorto uncaging it follows thatif the pitch axis of the aircraft is notparallel with the surface of the earth when gyro 60 is uncaged, the gyroin such a condition will give false information as far as roll isconcerned to the indicator 125. Stated otherwise if the pilot tends tokeep the needle 127 centered at the zero mark on the indicator when thehorizontal gyro was uncaged with its spin axis not parallel to theearths surface he will not be traveling, as desired, in a planeperfectly perpendicular to the earths surface but at an angle theretoequal to the amount of the angle between the wings of the aircraft atthe instant the roll-yaw gyro 60 was uncaged and the true horizontal. Itis the intent of the circuitry shown in FIGURE 3 to overcome thisdisadvantage. The disadvantage is overcome by providing a means ofpreventing the uncaging of the horizontal gyro 60 until the wings of theaircraft are level. Additional means, comprising the subject matter of aco-pending application of Theodore J. Wilson, Serial No. 553,152, filedSeptember 8, 1955, comprise an overriding mechanism which allows thehorizontal gyro 60 to be uncaged after a suitable'time delay even if thewings arent level so that the information from the horizontal gyro 60may be used. Thus some information, even if erroneous, will be presentedto the indicator which is preferable to no information at all. This willbe better understood by referring to the description below. It is notedthat a group of additional relays are added in FIG- URE 3 to thecircuitry of FIGURE 2. An auxiliary transfer relay 400 has a winding401, movable switch blades 402, 405, 408, and 410; in contacts 403, 406,409; and out contacts 404, 407, and 411. An auto level control relay 420has a winding 421; movable switch blades 422, 424, 426, and 428; incontacts 423, 425, 427, and 429; and out contact 430. A roll sensorrelay 430 has a coil 431 connected to in contacts 425 and 427 of autolevel control relay 420, a movable switch blade 432 and a pair of fixedcontacts 433 and 434. Roll sensor relay 430 is physically designed sothat when it is receiving no energization the movable switch blade 432is positioned as shown intermediate of fixed contacts 433 and 434. Whenit does receive an energization, even of low magnitude, it causes switcharm 432 to be displaced one way or the other depending upon the sense ofthe energization so as to complete a circuit between the movable bladeand one of the fixed contacts. An auxiliary uncaged relay 440 has a coilparalleled by a condenser 442, a movable switch blade 443 and an outcontact 444. A thermal override relay 450 has a heating element 451grounded at one end as at 50, a bimetallic heat responsive member 452serving as a movable switch blade, and a fixed contact433 adapted tocooperate with movable switch member 452. Relay windings 40, 42, and 44are grounded as at 50 on one side thereof. It will be noted that thelead 32' leading from the roll pick-off potentiometer wiper 32 of thevertical gyro no longer is switched by the indicator transfer relay 200but is led to out contact 411 of auxiliary indicator transfer relay 400as well as to the movable switch blade 424 of the roll sensor relay 430.Further, it will be noted that lead 224' leading from the roll centeringpotentiometer 222 no longer is switched by the indicator transfer relay200 but instead is led directly to out contact 407 of auxiliary levelcondition of the wings at that time, this will be sensed by the rollpick-off potentiometer so as to develop a signal in winding 431 of theroll sensor relay 430 so as to pull the same in and complete a circuitbe-. tween its movable switch blade 432 and one of its fixed contacts433 and 434. A lead 412 connects the ungrounded side of the winding 421of the auto level control relay 420 to conductor 253, said conductor 412also connecting movable switch blade 402 of the auxiliary indicatortransfer relay to conductor 258. Thus during the operation of thesystem, when conductor 258 becomes energized either due to thecompletion of the timing cycle or by moving the angle selector switch 96to position 3, auto level control relay 420 is energized. A lead 413provides a connection between lead 306 and out contact 430 of the autolevel control relay 420. Since lead 366 is energized wheneverstartswitch 302 is closed, it follows that voltage will be availablealso at said out contact 430. Prior to the auto level control relaybeing energized the auxiliary uncage relay 440 is energized from saidcontact 430 through movable switch blade 428 of the auto level controlrelay 420 and thence through a conductor 414. This breaks the circuitbetween movable switch blade 443 and out contact 444 of the auxiliaryuncaged relay 440.

Operation 0 FIGURE 3 Upon the completion of the timing cycle (ormovement of angle selector switch 96 to position 3) conductor 258becomes energized thus energizing the auto level control relay 420.Movable switch blade 422 of the auto level control relay 420 is alsoenergized from lead 412 from lead 258 and when the auto level controlrelay 420 pulls in it applies voltage to in contact 423 and thencethrough conductor 415 to the movable contact blade 432 of the rollsensor relay 430, movable contact blade 443 of the auxiliary uncagerelay 440 and switch blade 452 of the thermal override relay 450.Voltage also is applied to movable switch blade 402 of the auxiliaryindicator transfer relay 400, and since the latter is deenergized atthis point, allows voltage to be transferred out through the out contact404 to heating element 451 of the thermal override relay 450. Thiscauses switch blade 452 to gradually move towards fixed contact 453thereof. If the .wings of the aircraft are level roll sensor relay willnot be energized and hence no circuit will be established betweenenergized switch blade 432 and the fixed contacts 433 and 434. Auxiliaryuncage relay 440 will then be denergized allowing energized switch blade443 thereof to engage out contact 444 thereof applying voltage toconductor 353 so as to energize the uncage relay 86 and thus allow thehorizontal gyro 60 to uncage. It will be noted that conductor 353 isalso connected to the fixed contact 453 of the thermal override relay450 as well as to the coil 401 of the auxiliary indicator transfer relay400 and the in contact 403 thereof. Thus at the same time the horizontalgyro 60 uncages the auxiliary transfer relay 400 is energized whichtransfers the indication of the vertical needle 127 of indicator fromroll as sensed by the vertical gyro 10 to yaw-roll as sensed by thehorizontal gyro 60. However, if the wings of the aircraft are not levelat this point a voltage will be developed in roll sensor relay winding431 so as to cause displacement of switch blade 432 one direction or theother completing a circuit for energizing auxiliary uncage relay winding441 through a conductor 416, in contact 429 of the auto level controlrelay 420, and conductor 414 to the auxiliary uncage relay 440. Thepurpose of condenser 442 is to prevent the auxiliary uncage relay 440from becoming deenergized after theauto level control relay pulls inassuming there is a nonwings level condition. To explain, before theauto level control relay pulls in the auxiliary uncaged relay isenergized through out contact 430 thereof to lead 306. When the autolevel control relay pulls in and the wings are not level thenimmediately there is a new energization circuit for the auxiliary uncagerelay and the condenser 442 provides a sufiicient time lag in 13dropping out of said auxiliary uncage relay so asto pre-. vent theswitch blade 443 from coming in contact with the out contact 444 thereofso as to uncage the horizontal gyro. H

As soon as the pilot gets the wings of the aircraft level there nolonger willbe a signal developed in winding 431 of the roll sensor relayso that switch blade 432 will be moved to its center position so as todeenergize auxiliary uncage 446 and allow the horizontal gyro 60 touncage as well as energizing auxiliary indicator transfer relay 409. Itwill be noted that when auxiliary indicator trans: fer relay 400 doespull in a holding circuit is completed between movable switch blade 402and in contact 403 thereof.

If the pilot does not get the wings of the aircraft level within asuitable time, the thermal override relay 450 provides a means ofoverriding the roll sensor relay 430 in the following manner. It wasabove noted that as soon as the auto level control relay 420 wasenergized the thermal override relay heating element 451 was alsoenergized. Thus the switch blade 452 gradually moves towards fixedcontact 453. After a suitable time delay, contact is made between blade452 and fixed contact 453 thus uncaging the horizontal gyro 60 as wellas energizing auxiliary indicator transfer relay 400.

It will be observed that this apparatus shown in FIG- URE 3 serves thepurpose of delaying the switchover of information to the vertical needle127 of the indicator 125 until the wings of the aircraft are level oruntil a suitable time delay has been reached as the case may be but doesnot affect the transfer of information to the horizontal needle 129 ofthe indicator 125 from pitch of the aircraft as sensed by the verticalgyro to acceleration of the aircraft along its vertical axis as sensedby accelerometer 120.

While I have shown. and described a specific embodiment of thisinvention, further modifications and improvements will occur to thoseskilled in the art. I desire it to be understood, therefore, that thisinvention is not limited to the particular forms shown and I intend inthe appended claims to cover all modifications which do not depart fromthe spirit and scope of this invention.

What I claim is: Y

1. In an attitude responsive system for a dirigible craft havinglongitudinal, lateral, and yaw axes: a first gyro having a spin axisnormally parallel to said yaw axis of said craft and sensing deviationsof said craft about said longitudinal and lateral axes, said gyro havingpickolf means responsive to said deviations about said longitudinal andlateral axes; a second gyro having a spin axis normally parallel to saidlateral axis of said craft and sensing deviations of said craft aboutits longitudinal and yaw axes, said second gyro having pickoif meansresponsive to said deviations about said longitudinal and yaw axes;accelerometer means positioned on said craft and sensing accelerationsof said craft along its yaw axis, said accelerometer means includingpickoif means responsive to said accelerations; signal responsive means;means for caging and uncaging said second gyro, means for connectingsaid pickofr" means of said first gyro to said signal responsive meanswhile said second gyro is caged so that said signal responsive meansrespond to deviations of said craft about its lateral and longitudinalaxis; and means for disconnecting said pickoff means of said first gyrofrom said signal responsive means and for connecting said pickoif meansof said second gyro and said pickoif means of said accelerometer to saidsignal responsive means when said second gyro is uncaged so that saidsignal responsive means respond to deviations of said craft about itslongitudinal and yaw axes and accelerations of said craft along its yawaxis.

2. Apparatus as defined in claim 1 further characterized by meanscontrolling the uncaging of said second gyro so that said second gyromay be uncaged only when said lateral axis of said craft issubstantially horizontal.

3. .In a control system. for a dirigible craft having longitudinal,lateral, and yaw axes: a first gyro having a spin axis normally parallelto said yaw axis of said craft and sensing deviations of said craftaboutsaid longitudinal and lateral axes, said gyro having pickoif meansresponsive to said deviations about said longitudinal and lateral axes;a second gyro having a spin axis normally parallel to said lateral axisof said craft and sensing deviations of said craft about itslongitudinal and yaw axes, said second gyro havingpickotf meansresponsive to said deviations about said longitudinal and yaw axes;signal responsive means; means for caging and-uncaging saidsecondgyro;means for connecting said pickoff means of said first gyro to saidsignal responsive means while said second gyro is caged sothat saidsignal responsivev means respond to deviations of said craft about itslateral and longitudinal axes; means for disconnecting said pickotfmeans of said first gyro from said signal responsive means and forconnecting said pickoif means of said second gyro-to said signalresponsive means when said second gyro is uncaged so that said signalresponsive means respond to deviations of said craftaboutitslongitudinal and yaw axes and means controlling the uncaging ofsaid second gyro so that said second gyro may be uncaged only-when saidlateral axis of said craft is substantially horizontal.

. 4. In an attitude responsive system for a dirigible craft having roll,pitch, and yaw axes: a first gyro having a spin axis normally parallelto said yaw axis of said craft and sensing deviations of said craftabout said roll and pitch axes, said gyro having signal producing meansresponsive to said deviations of said craft about said roll and pitchaxes; a second gyro having a spin axis normally parallel to the pitchaxis of said craft and sensing deviations of said craft about its rolland yaw axes,'said second gyro havingsignal producing means responsiveto said deviations of said craft about said roll and yaw axes; signalresponsive means; means connecting said signal producing means of saidfirst gyro to said signal responsive means so that said signalresponsive means responds to deviations of said craft about its roll andpitch axes; means for disconnecting said signal producing means of saidfirst gyro from said signal responsive means and for connecting saidsignal producing means of said second gyro to said signal responsivemeans so that said signal responsive means respond to deviations of saidaircraft about its roll and yaw axes and means controlling theconnection of said signal producing means of said second gyro to saidsignal responsive means so that said connection may be made only whensaid pitch axis of said craft is substantially horizontal.

5. In a control system for a dirigible craft having roll, pitch, and yawaxes: a first gyro having a spin axis normally parallel to said yaw axisof said craft and sensing deviations of said craft about said roll andpitch axes, said gyro having signal producing means responsive to saiddeviations of said craft about said roll and pitch axes; a second gyrohaving a spin axis normally parallel to said pitch axis of said craftand sensing deviations of said craft about its roll and yaw axes, saidsecond gyro having signal controlling means responsive to saiddeviations of said craft about said roll and yaw axes; signal responsivemeans; accelerometer means positioned on said craft and responding toacceleration of said craft along its yaw axis, said accelerometer meansincluding signal controlling means for developing a signal indicative ofsaid accelerations; means for connecting said signal producing means ofsaid first gyro to said signal responsive means; and means fordisconnecting said signal producing means of said first gyro from saidsignal responsive means and for connecting said signal controlling meansof said second gyro and said accelerometer to said signal responsivemeans so that said signal responsive means respond to deviations of saidcraft about its roll and yaw axes and accelerations of said craft alongits yaw axis.

6. Apparatus as defined in claim further characterized by meanscontrolling the connection of said second gyro to said signal responsivemeans so that said connection may be made only when said lateral axis ofsaid craft is substantially horizontal.

7. In a control system for a dirigible craft having roll, pitch, and yawaxes: means for sensing angular deviations of said craft about said axesand for sensing accelerations along said yaw axis; signal means operatedby said sensing means; signal responsive means; and meansinterconnecting said signal means and said signal responsive means sothat said signal responsive means selectively respond to either pitchand roll of said craft, or.roll and yaw of said craft and accelerationof said craft along said yaw axis.

8. In a control system for a dirigible craft having roll, pitch, and yawaxes: means for sensing angular deviations of said craft about said axesand for sensing accelerations of said craft along one of said axes;signal means operated by said sensing means; signal responsive means;and means interconnecting said signal means and said signal responsivemeans so that said signal responsive means selectively respond to eitheracceleration. of said craft along said one of said axes andangulardeviations of said craft about the other two of said axes orangular deviationsof said craft about two ofsaid axes.

9. In a system for assisting a pilot to control an aircraft having roll,pitch, and .yaw axes: a vertical gyro rcsponsive to pitch and, roll of,said aircraft and including signal producing means for developingsignals according to the pitch and roll of said aircraft; a horizontalgyro responsive to roll and yaw of said aircraft and including means forproducing signals proportional to the roll and yaw of said aircraft; an,accelerometer responsive to accelerations of said aircraft along its yawaxis and including means for producing a signal proportional to saidaccelerations; visual indication means having twoindependent indicatingparts; means normally caging said horizontal gyr0;,tim-

ing means; means for actuating said timing means so as to commence atiming cycle; means connecting said signal producing means of saidvertical gyro to said indication means during said timing cycle so thatone part ofsaid indicating means indicates pitch of said aircraft andthe other part indicates roll of said aircraft; and means actuated bysaid timing means at the end of said timing cycle for disengaging saidmeans normally caging said horizontal gyro, for disconnecting saidsignal producing means of said vertical gyro from said indication means,and-forconnecting the signal producing means of said accelerometer tosaid one part of: said indication means and the signal producing meansofsaid horizontal gyro to said other part of said indication means.

10. Apparatus as defined in claim 9 further characterized by meanscontrolled by said vertical gyro for-controlling the uncaging of saidhorizontal gyro so that said horizontal gyro may be uncaged only whenthe signal produced from the roll signal producing means of saidvertical gyro is substantially that of a wings level flight attitude ofsaid aircraft, the transfer of indication on said other part of saidindication means from said roll signal producing means of said verticalgyro to the roll and yaw signal producing means of said horizontal gyrobeing delayed until said horizontal gyro is uncaged.

References Cited by the Examiner UNITED STATES PATENTS 2,554,512 5/51Varian 244-77 X 2,555,019 5/51 Webb 318-489 2, 13,350 10/52 Kellogg 343107 2,649,264 8/53 Slater 244 71 FERGUS S. MIDDLETON, Primary Examiner.NORMAN H. EVANS, Examiner.

8. IN A CONTROL SYSTEM FOR A DIRIGIBLE CRAFT HAVING ROLL, PITCH, AND YAWAXES; MEANS FOR SENSING ANGULAR DEVIATIONS OF SAID CRAFT ABOUT SAID AXESAND FOR SENSING ACCELERATIONS OF SAID CRAFT ALONG ONE OF SAID AXES;SIGNAL MEANS OPERATED BY SAID SENSING MEANS; SIGNAL RESPONSIVE MEANS;AND MEANS INTERCONNECTING SAID SIGNAL MEANS AND SAID SIGNAL RESPONSIVEMEANS SO THAT SAID SIGNAL RESPONSIVE MEANS SELECTIVELY RESPOND TO EITHERACCELERATION OF SAID CRAFT ALONG SAID ONE OF SAID AXES AND ANGULARDEVIATIONS OF